This invention relates to automated banking systems, and more particularly to cash or negotiable instrument dispensing systems.
With the advent of computer controlled banking facilities wherein a number of remote automated teller stations are in communication with and controlled by a centrally located computer, certain transaction security problems have become increasingly important. More particularly, available telephone line monitoring devices and computer related equipment have been developed and used by computer thieves to secure funds from the bank systems, for example, through the use of fraudulently injected enabling signals for the cash dispensing portions of remote terminals, or through the simulation of valid transactions from points along the communication path between the computer and remote terminal.
In response to this problem, prior art systems have developed remote terminals where a customer enters a signal representative of a personal identification number (PIN), which is transferred to the central computer for recognition and which in turn authorizes the transaction to take place. This PIN is typically memorized by the user and may take the form of, for example, his social security number, his birth date or some other personal data known only to the customer and the bank. This PIN is used in conjunction with a magnetically encoded ("magnetic stripe") card which typically includes data representative of a customer account number, bank number, zone number, and, in some forms, an encrypted identification number which relates the PIN number to a customer information file (CIF) signal stored at the central computer. The encrypted identification number is often denoted as the PIN OFFSET.
In the operation of such prior art systems, the customer typically enters his PIN (via a keyboard) together with his magnetic card which is read by a card reader at the remote terminal with the resultant PIN and PIN OFFSET signals being transferred to the central computer by telephone lines. At the computer, those signals are compared with a customer information file (CIF) number stored in the computer memory which is used to identify the customer account and verify the identity of the customer. Typically, the central computer then transmits a transaction authorization signal over the telephone line to the cash dispenser at the remote terminal.
Because of the relative ease by which any of these signals on the telephone lines may be intercepted and/or simulated, practical systems in the prior art are generally provided with complex data encrypting devices whenever any signal such as the PIN, PIN OFFSET or transaction authorization signal are transmitted over the telephone line. Of course, the resultant encrypted signals are also subject to interception, but if the encryption algorithm is suitably complex, the probabilities are low that the decoding of particular signals may be accomplished by a thief. However, in the case of the authorization signal which is transmitted over the line, the mere duplication of this signal, in most cases, even though it is in encrypted form, is sufficient to activate the cash dispenser at the remote terminals. Accordingly, using the modern data processing equipment currently available, relatively sophisticated encryption techniques must be used to establish the security of the data passed over the transmission lines, and even when accomplished, the cash dispensing portion of the remote terminal is still vulnerable to simulated authorization signals.
Furthermore, in prior art systems, in order to enhance security, the remote terminal hardware which performs the encrypting and decrypting functions is generally located within the vault at the remote terminal for security purposes, thereby requiring that vault to be of sufficient size (and corresponding expense) to house that hardware in addition to the bill dispensing apparatus.
Accordingly, it is an object of the present invention to provide an improved cash dispensing system which maintains a relatively high level security while not requiring data encryption for signals passed over a communication path from a remote terminal to a central computer.